While, position locating method using GPS (Global Positioning System) is used in various technical fields and application fields, the use has a limit because accuracy of signal received from satellites are low depending on locations. Especially, GPS signal cannot be received in the interior and there is limit for application to interior position data locating service that is in spotlight recently.
Recently, due to rapid expansion of WLAN infrastructure, services that locate positions using Wi-Fi signal, which is transmission signal of WLAN AP, and without using GPS signal. That is, in the position locating service using Wi-Fi signal, a service provider obtains Wi-Fi fingerprint based on Wi-Fi signal that is transmitted from WLAN AP's that are fixedly installed indoors or outdoors, a Wi-Fi radio map database is built by linking coordinates of corresponding points to the obtained Wi-Fi fingerprints, and a service environment for locating positions is provided. Then, when a service subscriber receives Wi-Fi signal at an arbitrary point, he can locate the position of the desired point referring to the Wi-Fi radio map database.
The biggest issue to provide such service that enables locating positions using Wi-Fi signal is how to build a reliable Wi-Fi signal map.
As prior art for building Wi-Fi signal map, the building technology by Skyhook company is known. This technology collects a pair of GPS signal and Wi-Fi fingerprint that includes AP unique data through war driving, estimates AP position using the accumulated data, builds an Wi-Fi signal map based on the estimated AP position data, and uses this in the position location service. This method, known as ‘WPS,’ has disadvantages that it requires a lot of cost and time, but still the accuracy is not high as the average error distance is almost 40 m. Also, because it collects Wi-Fi fingerprint while moving with a vehicle, it has clear limit in collecting Wi-Fi fingerprint for AP's installed indoors.
This Applicant suggested a method for effectively securing AP position data through Korean Patent No. 10-1091804 (“KR 804 Patent,” hereinafter) that was filed as a patent application on Dec. 15, 2009, and registered on Dec. 2, 2011. The technology disclosed in ‘KR804’ Patent is a method for utilizing active participation of service users. When an arbitrary mobile terminal collects Wi-Fi fingerprint, it requests the user who carries the mobile terminal to input location data. When the user inputs the location data, the mobile terminal stores the location data input that it received and Wi-Fi footprint together, and then transmits them to a service provider. The service provider can use them to build Wi-Fi signal map, and estimate the location data of AP more accurately.
However, such method requires active participation of users who carry mobile terminals as prerequisite. Because most users respond very passively in inputting location data, there is a problem of low effectiveness. Also, because the location data input by users is symbolic data, there is limit that absolute position coordinates are not obtained.
Upon identifying the limit of securing AP position data by user participation, this Applicant suggested a new method for effectively securing AP position data through Korean Patent No. 10-1144016 (“KR 016 Patent,” hereinafter) that was filed as a patent application on Jul. 20, 2010, and registered on May 2, 2012. The technology disclosed in ‘KR106’ Patent is a method that collects position data and Wi-Fi fingerprint of AP using house appliances that are installed at fixed indoor positions and connected to the Internet. That is, under a premise that house appliances connected to the Internet (TV, set top box, refrigerator, etc.) include installed modules that collect Wi-Fi fingerprints and transmit them to a remote server that are preset, and the location data for corresponding appliances can be obtained from the businesses which installed the appliances, each appliance is controlled to collect Wi-Fi fingerprints periodically and to transmit them to a remote server for building Wi-Fi signal map, and the remote server refers to appliance-unique data from signals received from the appliances, links them to pre-obtained data for installation locations of the appliances, and builds the Wi-Fi signal map.
However, there is a problem that it takes long time before realizing mass distribution of appliances on which Wi-Fi fingerprint collecting modules are installed, and have functions to transmit Wi-Fi fingerprints to the remote server.
The present invention solves those problems of the above prior arts, and proposes a new method that has little difficulty in performing the function of collecting Wi-Fi fingerprints, and collects Wi-Fi fingerprints using mobile terminals, the spreading of which has been increasing explosively recently, especially, smart phones. On the other hand, the method proposed by the present invention has effects that are distinct from prior art because, unlike ‘KR 804 Patent,’ in which location data that are directly input with mobile terminals by users who actively participate are used, it uses Wi-Fi fingerprints collected with mobile terminals, while the user is unconscious of the situation, and enables building a Wi-Fi signal map.